1. Field of the Invention
The present invention relates to a tantalum capacitor, more particularly, in which a capacitor body has a greater usable area and a tantalum wire is disposed to achieve miniaturization of the tantalum capacitor.
2. Description of the Related Art
Tantalum Ta carries mechanical and physical properties such as high melting point, and superior ductility and corrosion resistance, thus widely utilized across the industry, including electrics and electronics, mechanics, chemistry, medicine, space and military field. Notably, of all metals, tantalum allows formation of a most stable anode oxidized film, thus broadly used as a material for an anode in a small capacitor. Moreover, tantalum has been drastically increased in use by 10% annually due to rapid development of IT industry such as electronics and telecommunication.
Generally, a capacitor is an electrical device that can store energy temporarily. In the capacitor, two conductive plate electrodes are closely spaced with each other, separated by a dielectric, and electric charges build up on each plate electrode. That is, the capacitor is used to obtain capacitance by storing electrical charges between the two conductors.
A tantalum capacitor utilizes pores generated when a tantalum powder is sintered and cured. For this tantalum capacitor, an oxidized tantalum Ta2O5 is formed by anode oxidization on a surface of tantalum which acts as an electrode metal. Then, a manganese dioxide MnO2 layer is formed as an electrolyte on the oxidized tantalum which serves as a dielectric. Also, a graphite layer is formed on the manganese dioxide MnO2 layer, and a metal layer is formed on the graphite layer to derive a cathode electrode.
FIGS. 1A and 1B are a front view and a plan view illustrating an internal structure of a conventional tantalum capacitor, respectively.
Referring to FIGS. 1A and 1B, the conventional tantalum capacitor includes a rectangular parallelepiped capacitor body 11 containing tantalum powder, a tantalum wire 13 partially inserted into the capacitor body, a cathode lead frame 12, a cathode lead frame 12 connected to the capacitor body 11 and an anode lead frame 14 connected to the tantalum wire 13.
The tantalum wire 13 is bent twice perpendicularly at a portion not inserted into the capacitor body 11. Such bending allows the tantalum wire 13 to be directly connected to the anode lead frame 14.
Carbon and silver are applied on the capacitor body 11 and the cathode lead frame 14 is connected to the capacitor body 11 by a silver adhesive 12a. The tantalum wire 13 may be bonded to the anode lead frame 14 by one of spot welding, a conductive paste and laser welding.
In this tantalum capacitor structured as above, a larger volume of the capacitor body enhances a usable area of the capacitor but increases a physical volume thereof, thereby hampering miniaturization of the capacitor.